Typically, excavator buckets and the like have a base or floor with a cutting edge or lip to which ground engaging tools are fitted to engage the ground or spoil which is to be excavated or loaded as the case may be and to protect the lip from wear. Commonly, the ground engaging tools have a number of components. The first component, often called the nose, nose base, nosepiece or nose mount, is usually fixed in a permanent or semi-permanent manner to the base of the bucket by welding and protrudes forward from the lip. The second component is releasably mounted on or to the nose so that it can be replaced when it reaches a predetermined wear condition. In some types of equipment the second component is the cutting tip, tooth or tooth point which engages the ground at its front edge and suffers the main wear, while in other equipment, the second component is an adaptor to which a third component being the cutting tip or tooth is releasably fitted which in turn suffers the main wear while the adaptor suffers lesser wear. Thus, it will be understood that while the tooth in a three component system will have a much shorter life than the adaptor the adaptors themselves do eventually wear out and have to be replaced. Even the nose may wear out long before the bucket floor and walls and have to be replaced but in the case of the nose, it can be cut away from the base and replaced by new noses which can be welded to the base but that requires substantial downtime for a fairly substantial operation. In the case of a two component system, while the releasable tooth can be replaced relatively easily, if the nose wears out, a fairly substantial operation is required to replace it as with a three component system.
Typically, the nose includes a forwardly extending protuberance which is adapted to engage in a complementary cavity provided in the tooth or the adaptor in a three component system. In some prior art systems, the protuberance includes a tapered portion which is often referred to as the “cone”. In this specification, the term “cone’ is also used to refer to the tapered portion even though it may not be conical in shape.
In a two component system, the adaptor has a cavity opening at one end in which the complementary protuberance on the nose engages and a protuberance at the other end which is adapted to engage in the complementary tooth cavity. The two components are commonly releasably secured together by one or more locking pins which lock the tooth and the underlying adaptor together or the adaptor and the underlying nose in the case of a three component system. There are various securing systems available which are commonly referred to as retaining systems.
In one known retainer system, a tapered pin is driven through aligned holes extending through the tooth and the adaptor from top to bottom or the adaptor and the nose. However, the hole causes a weakness in the nose or the adaptor in a three component system which leads to failure. In another case, two opposed relatively short locking pins located in the nose are arranged to be extended into complementary holes or openings in the opposed side walls of the tooth or adaptor mounted on the nose.
It will be appreciated that the cavities and protuberances are shaped to inhibit relative movement between the engaging components when in operation, although the presently known systems do not inhibit relative movement as well as desired. Further, the presently available retaining systems do not provide the reliability or efficiency of operation desired.
In this specification, unless the context clearly requires a different meaning, the term forward and its derivatives are to be understood as being in the direction of movement of the tooth or bucket when digging or filling the bucket with spoil. Terms such as upper, lower, side, front, rear, and the like are to be understood in the context of the tooth digging so that the leading edge of the tooth is the front of the tooth.